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Eddie Current Electra Electrostatic Amplifier - Page 9

post #121 of 429

Selection and availability from a commercial perspective I surmise.

_________

 

I see you hijacked my S7 tubes for the Electra. Worthy cause.  wink_face.gif


Edited by Anaxilus - 7/15/12 at 6:27am
post #122 of 429
Thread Starter 
Quote:
Originally Posted by spritzer View Post

Why on earth is Craig still using 6SN7 in this amp when the 6SL7 is a far better tube for the job?  There is simply not enough low distortion gain in those tubes to have enough headroom for the feedback.  Feed it a SE signal and the amp will struggle with it, making it even more non-linear. 

 

Glad he saw sense WRT the EL34's a there is a simple reason why we use them and not 3d21's/6l6's/6BG6GA's/etc., they are the most linear of the bunch. 

 

I guess 6SL7s are nice option because it's easier to get some really great ones for cheaper. But gain seems plentiful with the 6SN7s. I am running currently balanced though. I can see how the SE inputs may be an issue for people with sources with low voltage outputs and want to crank the thing up. Maybe the SE inputs should just be deleted... biggrin.gif

 

Arnaud should be fine with the SE inputs as it. I think his DAC outputs 3.1V.


Edited by purrin - 7/15/12 at 10:30am
post #123 of 429

The issue isn't with the amp being loud enough, even garbage like the B-10 and Egmont will go loud enough to blow out your ears from a two stage design.  The issue with gain is the lack of headroom for the feedback and nobody in their right mind would run an electrostatic amp without a full feedback loop.  Cut it short and you end up with similar issues as the SRM-727. 

 

Input voltage has nothing to do with the SE input issues.  If there isn't enough gain in the amp then it's unable to perform the phase splitting which is why amps like the WES and A-10 require extra tubes for the phase splitting.  Same issue with the ESX if you run it with anything but 6SL7's, channels are uneven in volume since the two halves of each channel are fighting and the amp isn't stable. 

post #124 of 429
Thread Starter 

I'm sure between Andy and Craig, they will be able to figure out how much (or little gain) is necessary to trade off with how much feedback is required to keep the amp stable. From what I understand, these two guys have been working in the audio recording industry for a couple of decades now and hopefully know what they are doing. I've heard all many of issues being discussed between Andy and Craig through three iterations of the amp - and I should remind you that there have been significant changes throughout.

 

It's their asses and reputation on the line anyways.

post #125 of 429

Pretty sure this is Craig's first electrostatic amp and I am positive he would admit he is learning along the way.  He once said to me something to the effect that he would not choose EL34s for an electrostatic amp.  That's obviously changed.

 

Can't wait to hear it.


Edited by blubliss - 7/15/12 at 3:01pm
post #126 of 429
Quote:
Originally Posted by spritzer View Post

The issue isn't with the amp being loud enough, even garbage like the B-10 and Egmont will go loud enough to blow out your ears from a two stage design.  The issue with gain is the lack of headroom for the feedback and nobody in their right mind would run an electrostatic amp without a full feedback loop.  Cut it short and you end up with similar issues as the SRM-727. 

 

Input voltage has nothing to do with the SE input issues.  If there isn't enough gain in the amp then it's unable to perform the phase splitting which is why amps like the WES and A-10 require extra tubes for the phase splitting.  Same issue with the ESX if you run it with anything but 6SL7's, channels are uneven in volume since the two halves of each channel are fighting and the amp isn't stable. 

 

Can you explain what issues are you referring with this comment? "Cut it short and you end up with similar issues as the SRM-727."

I have the SRM-727 II with the SR-009 and IMO sounds great.

post #127 of 429
Thread Starter 

My understanding is as follows. The subject matter experts can feel to correct me if I am incorrect on any of the details.

 

The output stage of the SRM727 is outside of the feedback loop. I believe the feedback loop stops at the stage just prior to it. KG/Spritzer posted some mods which brought the output stage of the 727 inside the feedback loop, thereby reducing the bloom and increasing driver control.

 

This made the SRM727 play much better with the SR007s, especially the mk2s which are more prone to sounding bassy or even muddy. The funny thing is because of the bloomy nature of the SRM727, many people find it a good match with the SR009s, which can sound thin or lean on certain systems.

 

It's my understanding that Electra does have the output stage in the feedback loop.


Edited by purrin - 7/15/12 at 4:21pm
post #128 of 429

I think that if Electra can also use the 6SL7's that will be good because we can

find good and cheaper driver tubes easier, especially if we have to use a perfectly matched quad

in push-pull amplifier?  e.g. Tungsol 6SU7GTY's are cheaper and are probably better than the

Tungsol BGRP 6SN7's.   However if the Electra can only use the 6SN7's , it is OK with me too because

I can also find cheaper tubes with the same performance e.g. those 6F8G's

From what I know Craig uses four different techniques in his Electra and none of which are used in the

BHSE or DIY T2.  We should know more soon about the design and performances

So it is interesting to know the comparison between the Electra and other electrostatic amplifiers especially

in comparison with the BHSE or DIY T2  in terms of sound quality.  I think all of them have excellent sound quality

but different flavours.  The consumer will have more choices for their headphones

Please have more update on this interesting subject

 

This made the SRM727 play much better with the SR007s, especially the mk2s which are more prone to sounding bassy or even muddy.

The funny thing is because of the bloomy nature of the SRM727, many people find it a good match with the SR009s,

which can sound thin or lean on certain systems.

   With my system the modded 727 + SR009 may be a little bit bright,   I prefer the SR009 with the DIY T2  or at least with the Aristaeus


Edited by kiertijai - 7/15/12 at 4:40pm
post #129 of 429
Quote:
Originally Posted by purrin View Post

My understanding is as follows. The subject matter experts can feel to correct me if I am incorrect on any of the details.

 

The output stage of the SRM727 is outside of the feedback loop. I believe the feedback loop stops at the stage just prior to it. KG/Spritzer posted some mods which brought the output stage of the 727 inside the feedback loop, thereby reducing the bloom and increasing driver control.

 

This made the SRM727 play much better with the SR007s, especially the mk2s which are more prone to sounding bassy or even muddy. The funny thing is because of the bloomy nature of the SRM727, many people find it a good match with the SR009s, which can sound thin or lean on certain systems.

 

It's my understanding that Electra does have the output stage in the feedback loop.

 

Thanks for the expanation. I like my SRM-727 II/SR-009 combo a lot.

post #130 of 429

Those that don't pay attention to history are likely to repeat those mistakes.

The similarites between the current version of the electra and the es1 far

outweigh the differences.  Adding a 10db transformer for added gain has

a significant cost, and i'm not talking about money. 6sn7's are the wrong

tubes for this particular job. All the experience one may have about other

parts of audio have little relevance when trying to do 1kv voltage swings

and 60db of gain.

 

At some point craig will have to do it right, and the cost will go up.

For example the output tubes have to have their own filament supply

and that is close to 7 amps at 6.3v.  The plastic bulkhead connectors

can't handle that, so different connectors must be used.

 

A regulated power supply is also required otherwise the bias on

the output tubes can drift. Significant drift. In excess of 50 volts.

Having to rebias the output tubes every few hours gets to be a

pain in the neck after a while.

 

So when it hits $7k do not be too surprised.


Edited by kevin gilmore - 7/16/12 at 4:09am
post #131 of 429

That is pretty much it. Granted, EC can make above average dynamic amps but electrostatics bring new challenges into play and even the small details start to matter quite a bit.  Add to this the most resolving transducers money can buy and only the best will do. 

 

Quote:
Originally Posted by musicman59 View Post

 

Can you explain what issues are you referring with this comment? "Cut it short and you end up with similar issues as the SRM-727."

I have the SRM-727 II with the SR-009 and IMO sounds great.

 

Purrin pretty much covers it but with the SR-009 this design issue is a good thing.  Think of it as two flawed designs coming together and masking each others issues.  Muddy top end with bloated bass on the amp meets a bright headphone with bass limitations. 

post #132 of 429
Quote:
Originally Posted by spritzer View Post

Think of it as two flawed designs coming together and masking each others issues.  Muddy top end with bloated bass on the amp meets a bright headphone with bass limitations. 

 

err..ooaaakaay..you are being full of it. But go ahead make your claim.  rolleyes.gif


Edited by sachu - 7/16/12 at 9:21am
post #133 of 429

Cute. You guys must've got an A in science class. 

 

Like someone already said, it's Craig and Andy's reputation on the line anyways. 

post #134 of 429
Quote:
Originally Posted by Questhate View Post

Cute. You guys must've got an A in science class. 

you must be new around here....

post #135 of 429
Quote:
Originally Posted by SoupRKnowva View Post

you must be new around here....

 

biggrin.gif

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